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Misinformed OH and S exposing workers to deafness risk

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The widespread use of personal sound exposure meters is leading to poor noise assessments that could be putting workers' hearing at risk, says a noise safety expert ahead of his October address to The Safety Conference in Sydney.

Ken Scannell of Noise and Sound Services says many occupational health and safety professionals are unwittingly missing workplace noise hazards due to the inappropriate application of the personal sound exposure meters (PSEM) or 'noise dose meters, according to Australian Exhibitions and Conferences .

Startling figures show noise is one of the workplace's most serious health risks.

"Occupational deafness is the second most common workplace disease and accounted for almost one third of occupational diseases in NSW in 2004/05, costing over $38,000,000 in that state alone," Mr Scannell said, "and this is ‘good’ compared to previous years. Between 1991 and 2005, the bill for the industrial damage of employee’s hearing reached a staggering $887,000,000 in NSW."

"But is it not just the financial cost. Irreversible hearing damage leads to communication difficulties, impairment of interpersonal relationships, social isolation and a real degradation of the quality of life. This is not just for the person who has suffered the damage but also their family, friends, work colleagues and society as a whole."

The release of a new Australian Standard for Occupational Noise Management last year highlighted the deficiencies of PSEM devices, according to Mr Scannell.

"One of the common misconceptions is to assume that the use of noise dose meters to obtain noise level measurements is better than taking samples with hand held sound level meters," he said.

"It makes perfect sense to use a personal exposure meter to assess many hazards, like dust and radiation, but noise is different."

Mr Scannell points to three issues with the use of PSEM devices – the effect of averaging, the need to assess all noise sources and the potential for distorted results.

"I work with a lot of councils and their employees can go from quiet offices to standing next to a jack hammer," he said. "If you simply took the results from a PSEM worn by a person who had 10 minutes' exposure to the jack hammer and eight hours in a quiet office, you would assume noise levels were acceptable. Clearly, that's far from the truth."

The hazards in workshops with a lot of different equipment are also difficult to assess with a PSEM.

"PSEMs are often mistakenly preferred by non-acousticians as they can obtain measurements over the full working day," Mr Scannell said. "What is not understood is that this is only then a ‘snap shot’ on their exposure on that particular day. By measuring the noise level of all machines likely to be used by any of the employees with a hand held sound level meter, the risk of hearing can be calculated and assessed for any realistic scenario that could occur.\"

Finally, he says, PSEM readings can be distorted by their wearer's own behaviour.

"Shouting across the microphone, tapping the microphone, taking the meter off for short periods and not directing the microphone at the noise source will all give you a false picture of exposure levels," said Mr Scannell.

The newly revised AS/NZS 1269 and the NSW Occupational Health and Safety Regulation 2001 state that the measurement must be made at the position of the ears of the person being assessed. The ‘free field’ microphone needs to be pointed at the noise source.

The Australian Standard also deals with the effect chemicals in conjunction with noise can have on hearing and offers advice on preventing acoustic shock.

Mr Scannell will explain how to comply with the new standard and safeguard workers\' hearing at The Safety Conference during his address on October 19. The Safety Conference and The Safety Show will run from Tuesday 17 to Thursday 19 October at Southee Complex and The Dome, Hall 2 respectively at the Sydney Showground, Sydney Olympic Park.

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